Silylating process and agent



Ser. No. 398,781

- 12 Claims. (Cl. 260-448.2)

ABSTRACT OF THE DISCLOSURE if Compounds containing acidic protons aresilylated by reacting the compounds containing acidic protons with asilyl compound having the formula wherein R, R and R" are monovalenthydrocarbon United States Patent radicals, R is in addition hydrogen andthe -'-SiR radical'and R in addition is hydrogen and the radical,wherein Z is selected from the class consisting of hydrogen, monovalenthydrocarbon radicals, and the aforesaid SiR group. The process of thisreaction is useful for the separation'and analysis of organic compoundscontaining acidic protons.

This application is a continuation-impart of my application, Ser. No.371,095, filed May 28, 1964, now abandoned, and assigned to the sameassignee as the present invention.

This invention is concerned with a process for transferring silyl groupsonto certain classes of compounds to make silylated derivatives. More.particularly, the invention relates to a process for silylatingcompounds containing acidic protons which comprises reacting the lattercompounds with a silyl compound having the formula where R, R and R" aremonovalent hydrocarbon radicals, R is in addition hydrogen and the SiRradical and R in addition is hydrogen and the radical, where Z isselected from the class consisting of hydrogen, monovalent hydrocarbonradicals, and the aforesaid SiR group, with R having the meaning above,and thereafter obtaining a compound whose acidic proton (hydrogen) issubstituted with a SiR group. The invention also includes the compoundN,N-bis (trimethylsilyl) formamide.

The term silyl group is intended to mean the grouping SiR where R hasthe meaning given above.

The term compound having acidic protons is intended to mean organiccompositions which have attached to a carbon atom thereofacidic-hydrogen-containing groups such as amines, amides, carboxylgroups, aliphatic alcoholic hydroxyl groups, phenolic hydroxyl groups,sil-anol groups, etc.; as well as compounds containing carbon-bondedacidic hydrogens, e.g., nitromethane, nitropropane, malononitrile, etc.

3,397,220 Patented Aug. 13, 1968 I ICC The term silyl donor is intendedto mean compounds of Formula I, while the term silyl acceptor isintended to mean the organic compound containing the acidic proton.

Silylation of amines, amides, lactams, carbamates, ureas, peptides, andcompounds containing hydroxyl functions has become a valuable tool forseparation and analysis. Replacing the protons by silyl groups can leadto derivatives of considerably higher vapor pressure which afterdistillation or vapor chromatographic separation can readily beconverted into the starting materials.

The silylation reactions are often desired to make dorivatives ofmixtures of compounds which are ditricultly separable from each otherbecause of a high degree of hydrogen bonding, which does not permitseparation of the individual'components by distillation; on the otherhand, the'silyl derivatives of many compounds have sufficiently lowerboiling points thereby permitting ready distillation or other physicalseparation.

In the past, the silylation reaction has involved the use of silyldonors which react sluggishly if at all at room temperature with thesilyl acceptors and it is only by employing relatively high temperatureswell above C. that any desirable rate of reaction is accomplished.Moreover, even if elevated temperatures are employed, it usuallyrequires relatively long periods of heating be tween the silyl donor andthe silyl acceptor to elfect the exchange of the silyl group, due insome respects to the necessity of removing lower boiling aminesresulting from the use of silylated amines as the silyl donor. Veryoften, the silyl acceptor suffers deleteriously if exposed to elevatedtemperatures, and this has often limited the use of many silyl donors.

It is accordingly one of the objects of this invention to effect asilylation reaction of compounds containing acidic protons.

It is still a further object of this invention to effect exchange ofsilyl groups between silyl donors and silyl acceptors rapidly andemploying less drastic conditions than has heretofore been required.

It is a still further object of the invention to effect silylation ofcompounds which can then be separated, purified, or otherwise processedand the silyl group thereafter readily removed to obtain the compoundsfree of the silyl group.

It is another object of the invention to effect silylation of compoundswhich heretofore could not be effected even under drastic conditions.

Other objects of the invention will become more apparent from thediscussion which follows.

Among the monovalent hydrocarbon radicals which R, R, R" and Z inFormula I may be are, cEor instance, alkyl radicals (e.g., methyl,ethyl, propyl, isopropyl, pentyl,

octyl, dodecyl, etc., radicals); alkenyl radicals (e.g., vinyl, allyl,crotyl, etc., radicals); aryl radicals (erg, phenyl, naphthyl, biphenyl,etc. radicals); azralkyl radicals (e.g., benzyl, phenylethyl, etc.,radicals); alkaryl radicals (e.g., xylyl, tolyl, ethylphenyl,methylnapht-hy], etc., radicals); cycloaliphatic (including unsaturated)radicals (e.g., cyclopentyl, cyclohexyl, cyclopentenyl, cyclohexenyl,etc., radicals); etc. It is readily apparent that the illustratedradicals all contain no more than 12 carbon atoms.

There are numerous ways for making compounds having the formula R-N- iR" SlRg and used as the silyl donor. If R, R and R" are monovalenthydrocarbon radicals, then one can make the compounds of Formula I *byreacting a trior-ganosilyl halide of the formula R SiX with a compoundof the formula in about equimolar proportions in the presence of ahydrohalide acceptor, often at ambient temperatures.

If R in Formula I is desired to be a SiR radical and R is desired to bea monovalent hydrocarbon radical, then one can react in a molar ratio of2 mols of the trior ganosilyl halide R SiX with 1 mol of a compound ofthe formula N Bri l-R" 'When R" is desired to be the and R is desired tobe a monovalent hydrocarbon radical in Formula I, one can react anorganocyanate of the formula R'NCO with a compound of the formula ZR3Si1 I-Z in the manner described in my copending application, Ser. No.371,119, filed May 24, 1964 and assigned to the same assignee as thepresent invention, now US. Patent 3,346,- 609, issued Oct. 10, 1967. Byreference, this application is made part of the disclosures andteachings of the instant application as to compounds of Formula I andmethods for making such compounds.

If R. in Formula I is hydrogen, and R and R are m-onovalent hydrocarbonradicals and R" in addition is the radical, then one can make compoundsof this type by reacting one mol of a triorganosilyl halide of theformula R SiX with one mol of a compound of the formula H-NH-h-R" in thepresence of a hydrohalide acceptor, to give compounds of formula .If R"in Formula I is hydrogen, R and R are monovalent hydrocarbon radicalsand R is in addition the SiR radical, then one can make the compounds ofthis type by reacting a trior'ganosilyl halide of the formula R SiX witha compound of the formula I? RNHGH in about cquimolar proportions in thepresence of a hydrogen hydrohalide acceptor to give a compound havingthe formula t R-N-C-H sin,

If in Formula I, R and R" are both hydrogen, then to arrive at such aformula, one would react equimolar proportions of a triorganosilylhalide of the formula R S1X with a compound of the formula i HNH-(-Hthereby giving a compound of the formula In all the syntheses recitedabove for making compounds of Forr'riula I, anhydrous conditions areemployed and the representations for R, R, R" and Z have the meaningsgiven previously. Among the hydrohalide acceptors which may be employedin the process for making the compounds of Formula I described aboveare, for instance, pyridine, ,triethylarnine, tributylamine, etc.Persons skilled in the art will have no difl'iculty in determining howto make the silyl donors of Formula I from the examples which follow andfrom prior art references which are more than adequate for the purpose.It is also apparent that'the. above directions provide for obviousvariations depending on the starting materials, and the representationsfor R, R, and R. V V

Typical of the conditions under which one can make silyl donors ofFormula I may be mentioned the following illustrative syntheses:

-One mol trimethylchlorosilane is reacted with one mol N-methylacetamidein the presence of pyridine to obtain a composition having the formulaCH3 0 i t (CH3)3S1N CH This reaction readily takes place upon mixing theingredients and heating to a temperature of from about 50- C., afterwhich the salt of the hydrohalide acceptor is removed and any excess ofthe reaction products is removed and the desired product isolated.

Other react-ions for making compositions used as a silyl donor involvesreacting 2 mols of trimethylchlorosilane and 1 mol of acetamide to givethe composition having the formula 0 [(CHahSflFN--CHQ again employing ahydrohalide acceptor and essentially the same conditions as describedabove.

When R" is desired to be the radical this can be accomplished byreacting, for example, phenylisocyanate withtrirnethylsilyldimethylamine to give a composition in accordance with myabove-identified patent application having the formula II CsH5N-C (C1192When R is desired to be hydrogen, this can be accomplished by reactingfor example 1 mol of trimethylchlorosilane with 1 mol of acetamide inthe presence of pyridine to obtain a composition having the formula 0HNH3CH3 Si(CHa) 0 H-N-H a)a using the same conditions as recited above.If N-methylformamide is employed, the" reaction of trimethylchlorosilaneunder such conditions would give the compound It will of course beapparent to those skilled in the art that various other means can beemployed to make'the compositions of Formula I. In addition totrimethylchlorosilane, the triorganosilyl group can be, for example,triphenylchlorosilane, tribenzylchlorosilane, triphenylbromosilane,trixylylbromosilane, triethylchlorosilane tributylchlorosilane, etc.Furthermore, various other organoisocyanates (e.g., toluene isocyanate,benzyl isocyanate, ethyl isocyanate, butyl isocyanate, etc.), as well asvarious triorganosilylamines (trimethylsilylamine, triphenylsilylamine,N-methyl trimethylsilylamine, etc.); various amides, etc., may be usedfor the purpose.

Included among the slyl acceptor compounds may be mentioned, forinstance, alcohols (e.g., ethanol, isopropan01, butanol, octanol, etc.);phenols (e.g., phenol, xylenol, cresol, ethyl-phenol, naphthol, etc.);amines (e.g., ethylamine, propylamine, dibutylamine, aniline, etc.);acids (e.g., acetic, propionic, butyric, benzylic, toluic, etc., acids);amides (e.g., acetamide, propionamide, benzamide, etc.); ureas (e.g.,urea, diphenylurea, thiourea, diethylurea, etc.); aminoacids (e.g.,glycine, alanine, cysteine,

histidine, etc.); sugars (e.g., sucrose, lactose, fructose, glucose,etc.); lactams; peptides; etc. 7

The silylation reaction of the present invention can be be carried outby simply mixing the silyl donor and the silyl acceptor compounds in asuitable colvent (usually in equimolar proportions although from 0.01 to3 or more molar excesses of each compound can be used), for instance,acetonitrile, acetone, chloroform, chlorobenzene, tetrachloroethane,carbon tetrachloride, benzene, etc., stirring the mixture preferably atroom temperature, about 2030 C., and alternatively, if desired, atelevated tem.,

peratures of from about -100 C. or higher and thereafter isolating thesilylated compound. In many instances equilibrium reaction lies in thedirection of the desired silylated product; whereas in some instancesequilibrium can be shifted to the product side (i.e., silylated organiccompound) by allowing the desilylated donor compound to crystallize inthe reaction mixture after its silyl group is transferred to the silylacceptor compound. The separation of the product can be achieved by theusual means, for instance, extraction, sublimation, distillation, etc.The silylation reaction usually goes in a matter of minutes and, in someinstances, as fast as the time required for mixing the silyl donor andthe silyl acceptor compounds. although under such conditions, very oftenthe yield of silylated compound is either high or essentiallyquantitative, essentially complete conversion to the desired silylatedcompound is insured by continuing to stir the reaction mixture for timesranging from about 1 hour to 15 hours or more. I have found that thepresence of more than one triorganosilyl group on a nitrogen of thedonor com-pound increases the silylating reactivity of the donorcompound.

In order that those skilled in the art may better understand how thepresent invention may be practiced, the following examples are given byway of illustration and not by way of limitation. All parts are byweight, unless otherwise stated. Where analyses are given the values inparentheses are the theoretical values for the elements. Anhydrousconditions were observed in all examples.

Example 1 N-trimethylsilyl-N,N-diphenylurea was prepared by mixing 11.9grams phenylisocyanate and 16.5 grams N-trimethylsilylaniline (which inturn was prepared by reacting aniline with trimethylchlorosilane inequimolar proportions) in 10 cc. of dry hexane, and this mixture wasallowed-to stand at room temperature (about 2530 C.) for about 15 hours.The white crystalline product which precipitated was removed byfiltration, washed with dry hexane and dried. This yielded a productmelting at 7779 C., and was identified as being the desired compound asevidenced by the following analytical results: percent C: 67.5 (67.5):percent H; 6.9 (7.1); percent 6 Ni 9.8 (9.8). This compound willhereinafter be identified as silyl donor compound No- 1.

Example 2 The compound bis (trimethylsilyl)acetamide having the formulao Ha lN=[ a)a]z which is known to'exist in an equilibrium"relationshipwith its tautomeric form o-siwfim CHaC=N-Si(CHa)3 was prepared by mixingtogether 59 grams acetamide with 250 grams trimethylchlorosilane in 250grams of triethylamine. The mixture was heated at its reflux temperaturewith stirring under anhydrous conditions for about 15 hours. Aftercooling, 500 cc. of diethyl ether was added to facilitate filtration.The filtrate (separated from the hyd-rohalide acceptor salt)wasfnactionally distilled to give bis(trimethylsilylacetamide boilingat' 7l 73 C./ 35 mm. This compound will hereinafter be identified assilyl donor compound No. 2.

Example 3 To a stirred solution of 10.3 grams oftrimethylsilylmethylamine (prepared similarly as in Example 1 byreacting trimethylchlorosilane with methyl amine) in 20 cc. anhydroushexane was added slowly 11.9 grams of freshly distilled phenylisocyanateover a period of 10 minutes during which time the temperature of themixture rose to about 70 C. After cooling to room temperature, a mass ofcolorless crystals were obtained and separated. Subsequent purificationgave a product melting at 72-75 C. This material was identified ashaving the formula as evidenced by the analyses which were as follows:percent C; 59.4 (59.4); percent H: 8.1 (8.2); percent N: 12.7 12.6).

Example 4 In this example phenylisocyanate was reacted with his(trimethylsilyl)methylamine (prepared by reacting 2 molstrimethylchlorosilane with 1 mol methylamine) in the same manner as inExample 3 to produce N-methyl-N- phenyl-N,N'-bis(trimethylsilyl)ureahaving the formula whose identity was established by the followinganalysis: percent C: 56.6 (57.0); percent H: 8.9 (8.9); percent N: 9.8(9.5); percent Si: 19.3 (19.1).

Example 5 About 2.27 parts N-(dimet-hylphenylsilyl)aniline (prepared byreacting dimethylphenylchlorosilane with aniline) were mixed with 1.19parts of phenylisocyanate and heated-at C. in an atmosphere of drynitrogen with stirring for about 1 hour. The product thus obtained wasrecrystallized from a dry mixture of a 1:1 weight ratio of hexane andbenzene to give a product melting at 111- 113 C. This composition wasidentified as having the formula as evidenced by the analyses which wereas follows: perwhile Table 2 shows the analyses for these silylureas,establishing that the compositions were in fact obtained.

methylsilyl piperidine. Each of the silyl donors was reacted inequimolar concentrations with the silyl acceptor.

The following equations show the reactions as they were carried out,together with a notation under each equation as to the rate ornon-reactivity of the reagents:

H n o H5-N-g N o6H, CH;--NHONHCH;

Si(CHa)a O CHz-N-(J-NH-CH:

Si(CHa)s (100% conversion after 2 minutes) TAB LE 1 Test N o. AmineReactant Isocyanate Product ii (in (CH3) 2N-Si(CHa)3 osHsNCO CeH5NC-NCH3) 2 Si(CHa)a 6b (CH3) (caHs) NSi(CHa) 3 CaHsN CO C tH-NC NC 5H5 Si 0a) a if (CH3)2NSi(CH P-CH3CQH4NCO pCH3CsH N-CN(CH3)2 Si C H93 l 6d CoH1-NH?i(CH3)2 CeH5NCO CoHs-N--NH-CuHu ll 6e CeH NH--Si(CH m-CH; CsH4NCOmCH3CaH4NCNH-CaH5 ii (if CH NHSi(CH3)3 Ill-CHaCoEhNCOm'CH3-CGH4-N-C-NHCH Si C 3) 3 6g NH[S1(CH3) ]2 CeHaNCOCuH5-N-C-NHsi(CH3)3 siwmn The amine reactants were prepared by reactinga trihydroearbon substituted chlorpsilane, e.g., (CHmSiOl or(CHmCuHfiiCl with the appropriate amine containing a primary hydrogen toefiect removal of HCl and substitution of the trihydroearbon-substitutedsilyl group in place of the hydrogen.

TABLE 2 Analyses, Percent Elements Observed] Calculated 1 B.p. -82"C./0.5 mm.

The following examples illustrate the use of silyl donor compounds forsilylating organic compositions containing acidic protons. Anhydrousconditions were observed throughout the siiylation reaction.

Example 7 r 55 o 60 61 0 8 l 8 5 12 57119 ll lll 9 g 68.7/68.4 7. 311.49.5 g 9 5451 CH N 15 2335337? t 9.6 955 9.4 60. 2 e1.0 8.6/8.5 12.4/11.811.9/11.9 60 (3% Converslon after 3 days) 20 mm c, 0

(No reaction after 3 days) (1.

0 CH N 1-NHCHa a)a (10% conversion after 3 days) All of the above threereactions were carried out with stirring under the same conditions ofroom temperature and using acetonitrile as the solvent in which thereact- 9. ants were interacted. Where reaction took place in equationsa, b and d,'the by-products were N,N diphenylurea, aniline andpiperidine, respectively.

Example 8 This compound was identified by analyses, Which'shoWed:percent C: 39.0 (38.7); percent H: 8.0 (8.1); percent N: 11.3 (11.3). 7

Example 9 a mixture of 6.6 grams of malononitrile and 28.4 grams ofsilyl donor compound No. l in 50 cc. of dry benzene was stirred for 15hours at C. The precipitate of diphenylurea was removed by filtrationand after concentrating the filtrate, it was extracted Wih hot n-hexane.Upon cooling, there were obtained crystals of trimethylsilyl-substitutedtrimer of malononitrile melting at 170- 171 C., and having the structureAnalyses established this structure: percent C: 52.0 (52.1); percent H:7.3 (7.5); percent N: 20.2 (20.2); molecular Weight421 (417 theory).Hydroylsis in ethanol yielded the desilylated compound, a colorlesssolid melting at 400 C. (decomposition) as shown by the followinganalyses: percent C: 54.5 (54.5); percent H: 3.0 (3.2); percent N: 42.5(42.3).

Example 10 A mixture of 0.88 gram N,N-dimethylurea and 2.84 grams ofsilyl donor compound No. 1 suspended in 3 cc. of acetonitrile was warmedfor about 1 minute until a clear solution was obtained. Precipitation ofdiphenylurea started after a few minutes. The mixturewas stirred forseveral hours at 35 C., filtered, the solvent evaporated, and theresidue sublimed at 40 C./0.5 mm. to give a solid having a melting pointof 125-9 C. Analysis of the compound showed it to beN,N-dimethyl-N'-trimethylsilylurea, as evidenced by the analyses:percent C: 45.3 (45.0); percent H: 10.0 (10.0); percent N: 17.1 (17.5 v

Example 11 A suspension of 1 mole of thiourea in a solution of 1 mole ofsilyl donor compound No. 1 and 1.5 grams of acetonitrile were stirred at35 C. for hours. After this time, the thiorea had gone into solution anda precipitate of diphenylurea mixed with silylthiourea had formed. Themixture was heated to reflux, filtered, the solvent evaporated, and awhite residue obtained which, upon sublimation, yielded a compoundhaving a melting point of l55158 C. Analysis of the compound showed itto be N,N'-bis(trimethylsilyl)thiourea as evidenced by the analyseswhich showed: percent C: 38.1 (38.1); percent H: 9.2 (9.1); percent N:17.9 (17.7); percent Si: 25.6 (25.5).

Example 12 A mixture of 1 gram of guanidine and 14.5 grams of silyldonor compound No. and 30 cc. of acetonitrile formed a precipitate ofdiphenylurea immediately. The reaction was allowed to come to completionby stirring at 35 C. for 3 hours. Distillation of the product afterfiltration gave tris(trimethylsilyl)guanidine, this liquid boiling at 40C./0.5 mm.; the structure was identified by analyses which showed for CH N si percent C: 43.6 (43.5); percent H: 10.6 (10.6); percent N: 15.7(15.3).

Example 13 About 5 grams acetylacetone was mixed with 14 grams of silyldonor compound No. 1 and 25 cc. dry benezene. The precipitation ofdiphenylurea started in a few minutes. The reaction was completed bystirring at room temperature for 15 hours. The filtrate was distilled toobtain trimethylsilylacytylacetone (C H O Si) boiling at 102-3 C./ 35mm., as evidenced by the analyses which showed: percent C: 55.9 (55.8);percent H: 9.2 (9.3); percent Si: 16.0 (16.3).

Example 14 About 0.21 gram N.N'-diphenylurea was mixed With 1 gram ofDCC1 and 0.41 gram of silyl donor compound No. 2. The mixture wasstirred at 35 C. for about 2 hours. Diphenylurea was dissolved afterthis time. There was thus obtained the compoundbis(trimethylsilyl)diphenylurea.

Example 15 The mixing of equirnolar quantities of aniline and silyldonor compound No. 2 in DCC1 led to almost instantaneous quantitativeformation of N-trimethylsilyl aniline.

Example 16 When equimolar concentrations of 2,6-xylenol and silyl donorcompound No. 2 in a small amount of benzene were mixed together, anexothermic reaction resulted to give 2,6-dimethylxylenyl-trimethylsilylether.

Example 17 In this example, to a suspension of 0.29 gram of1,3-diphenyldisiloxanediol-1,3 in about 1 gram of carbon tetrachloridewas added 0.41 gram of silyl donor compound No. 2. A rapid reactionoccurred, as indicated by the disappearance of the diol and theformation of octamethyldiphenyltetrasiloxane which was established byits proton magnetic resonance spectrum to have the formula A mixture of1.5 grams of dimedone and 4.0 grams of silyl donor compound No. 2dissolved in about 3 cc. of benzene was allowed to stand at roomtemperature for about 15 hours. The colorless clear solution was thensubjected to a vacuum of 0.5 mm. and stirred at 35 C.Trimethylsilylacetamide sublimed into the colder parts of the apparatusand finally into a liquid nitrogen trap. The operation was finishedafter about 3 hours. The remaining colorless liquid crystallized at roomtemperature and was identified by NMR spectrum as beingtrimethylsilyldimedone.

Example 19 When the other products found in Table I of Example 6 areused as silyl donors with silyl acceptor compositions such as aliphaticalcohols, phenolic alcohols, hydroxy compounds, etc., the triorganosilylgroup is readily transferred merely by interaction of the silyl donorwith the silyl acceptor compound, at room temperature.

Example 20 A suspension of 1.1 grams of diketopiperazine in a solutionof 5.7 grams trimethylsilyldiphenylurea (silyl donor compound No. 1) in5 cc. of acetonitrile was stirred for Example 21 A suspension of 6.75grams of oxindole in cc. benzene was stirred with 21 grams ofbis(trimethylsilyl)- acetamide (silyl donor compound No. 2) underanhydrous conditions at 30 C. The oxindole went into solution withinabout 1 hour as it was converted into its disilyl derivative. Themixture was then fractionally distilled to obtain the productN,O-bis(trimethylsilyl)oxindole boiling at 8590 C./0.5 mm. and havingthe formula Si(CHa)a Example 22 N-trimethylsilylacetamide was preparedsimilarly as above by effecting reaction between 1 mol of acetamide and1 mol of trimethylchlorosilane, by heating in the presence of pyridineas the hydrohalide acceptor, at a 12 Example r The compound N,Nbis(trimethylsilyl) formamide having the formula {(CHalaSilrN-Hl-H wasprepared by adding 250 grams trimethylchlorosilane to a suspension of 45grams formamide in 550 grams of triethylamine. The reaction mixture washeated with stirring at its reflux temperature for about 12 hours, atthe end of which the precipitated triethylamine hydrochloride wasremoved by filtration. The remaining product was subjected to fractionaldistillation to obtain a compound which was identified as having theabovedescribed formula and boiling at 71-7 3 C./ mm. and a refractiveindex n =1.4395.

When the silylated formarnide of Example 25 was reacted in equimolarconcentrations with hydroquinone, there was obtained the disilylatedether of the hydroquinone, i.e., a hydroquinone ether in which there arepresent one trimethylsilyl group on each oxygen. This example shows themarked silylating reactivity of the disilyl formamide.

In addition to the above examples of silylation, one can also mix adisilylurea, e.g., N,N-bis(-trimethylsilyl)- N,N-diphenylurea with adipeptide, such as N-methyl- DL-alanylglycin in a suitable solvent, forinstance, acetonitrile, to give a trisilylpeptide according to thefollowing equation:

Si(CHa)a temperature of about C. for about 30 minutes. Afterprecipitation of the hydrohalide salt, the trimethylsilylacetamidederivative having the formula 0 H-N-Hl-OHi Si('CHs)a was obtained.

Example 23 In this example, the use of the trimethylsilylacetamide ofExample 22 as a silyl donor was demonstrated by first dissolving 2.46grams of 2,6-dipheny1phenol in 5 cc. dry benzene and then adding 1.35grams of the aforesaid trimethylsilylacetamide. The solution was stirredfor about 12 hours at room temperature under anhydrous conditions. Theprecipitated acetamide which formed was removed by filtration, thesolvent then removed and the white crystalline residue wasrecrystallized from dry nhexane to give 2,6-diphenylphenyltrimethylsilylether having a melting point of 108-109 C.

Example 24 A mixture of 0.29 gram of 1,3-dimethyl-1,3-dipheny1-disiloxanediol-1,3, 0.13 gram of the N-trimethylsilylacetamide ofExample 22 and 2 cc. benzene were stirred at room temperature underanhydrous conditions for 1 hour. The precipitate of acetamide wasremoved and after removal of the solvent, the reaction product was thenisolated and established to be octamethyldiphenyltetrasiloxane of theformula Land.

Such trisilylpeptides can then be converted to polypeptides.

Another instance where my process can be used is in the silylation of asugar, like sucrose, which may 'be effected by mixing 3 mols ofdisilylurea, e.g., N,N'-bis(trimethylsilyl)-N,N-dipheny1urea, with 1 molof sucrose in pyridine at room temperature, to givehexa-O-trimethylsilylsuc-rose within several minutes, which then may beseparated from impurties by distillation. Hy drolysis with aqueousalcohol affords the purified sucrose.

It will, of course, be apparent to those skilled in the art that inaddition to the ingredients given above, other silyl donors within thescope of Formula I and other silyl acceptors, again many examples ofwhich have been given above, many be employed without departing from thescope of the invention. The conditions whereby the silylation reactionis carried out may also be varied as is indicated previously by thedisclosures and examples.

What I claim as new and desire to secure by Letters Patent of the UnitedStates is:

1. The process for transferring silyl groups onto a silyl acceptorcompound containing at least one acidic proton which comprises reactingthe latter compound with a silyl donor compound having the formula:

SiRa wherein R is a monovalent hydrocarbon radical selected from theclass consisting of alkyl, alkenyl, aryl, aralkyl, alkaryl andcycloaliphatic radicals, R is a member of the class consisting ofhydrogen, a monovalent hydrocarbon radical selected from the classconsisting of alkyl, alkenyl, aryl, aralkyl, alkaryl and cycloaliphaticradicals or the SiR group where R is as above-defined and R 13 is amember of the class consisting of hydrogen, a monovalent hydrocarbonradical selected from the class consisting of alkyl, alkenyl, aryl,aralkyl, alkaryl and cycloaliphatic radicals and the radical where Z isselected from the class consisting of hydrogen, a monovalent hydrocarbonradical selected from the class consisting of alkyl, alkenyl, aryl,aralkyl, alkaryl and cycloaliphatic radicals or the SiR radical, whereinR is as above-defined, and the monovalent hydrocarbon radicalsrepresented by R, R, R and Z can contain up to and including 12 carbonatoms.

2. The process as in claim 1 in which the silyl donor compound isN-trimethylsilyl-N,N'-diphenylurea and the silyl acceptor compound isnitromethane.

3. The process as in claim 1 in which the silyl donor compound isN-trimethylsilyl-N,N'-diphenylurea and the silyl acceptor compound ismalononitrile.

4. The process as in claim 1 in which the silyl donor compound isN-trimethy1silyl-N,N-diphenylurea and the silyl acceptor compound isN,N-dirnethylurea.

5. The process as in claim 1 in which the silyl donor compound isN-trimethylsilyl-N,N'-diphenylurea and the silyl acceptor compound isthiourea.

6. The process as in claim 1 in which the silyl donor compound isN-trimet-hylsilyl-N,N-diphenylurea and the silyl acceptor compound isacetylacetone.

7. The process as in claim 1 in which the silyl donor compound isbis(trimethylsilyl)acetamide and the silyl acceptor compound isN,N'-diphenylurea.

8. The process as 'in claim 1 in which the silyl donor compound isbis(trimethylsilyl)acetamide and the silyl acceptor compound is aniline.

9. The process as in claim 1 in which the silyl donor compound isbis(trimethylsilyl)racetarnide and the silyl acceptor compound is2,6-Xylenol.

10. The process as in claim 1 in which the silyl donor compound isbis(trimethy1silyl)acetamide and the silyl acceptor compound isl,3-dimethyl-1,3-diphenyl-disiloxanediol-l,3.

11. The process as in claim 1 in which this silyl compound isN-trimethylsilyl acetamide and the silyl acceptor compound is2,6-diphenylphenol.

12. The compound N,N-bis(trimet hylsilyl)fonmamide.

References Cited UNITED STATES PATENTS 2,876,209 3/1959 De Benneville et211.

260-4482 XR 2,876,234 3/1959 Hurwitz et a1. 260-4482 XR 2,906,756 9/1959De Benneville et a1.

TOBIAS E. LEVOW, Primary Examiner.

P. F. SHAVER, Assistant Examiner.

